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340 6 bbl metering plates ?2 #2758263
04/01/20 02:04 AM
04/01/20 02:04 AM
Joined: Jan 2003
Posts: 1,686
s. e. pa.
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calrobb2000 Offline OP
top fuel
calrobb2000  Offline OP
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Joined: Jan 2003
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s. e. pa.

hi

i need 2 outboard metering plates for the 340 end carbs .

someone has drilled the originals ????

where can i get them ?

thank you !

Re: 340 6 bbl metering plates ?2 [Re: calrobb2000] #2758268
04/01/20 02:25 AM
04/01/20 02:25 AM
Joined: Aug 2003
Posts: 34,973
Bend,OR USA
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Cab_Burge Offline
I Win
Cab_Burge  Offline
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Joined: Aug 2003
Posts: 34,973
Bend,OR USA
Have you tried Holley yet? If not do that first, if they don't offer them still try Chicago Corvette in Chicago IL scope
I don't have their phone number anymore, sorry blush


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: 340 6 bbl metering plates ?2 [Re: calrobb2000] #2758291
04/01/20 08:04 AM
04/01/20 08:04 AM
Joined: Jan 2003
Posts: 9,249
Central,PA
62maxwgn Offline
master
62maxwgn  Offline
master

Joined: Jan 2003
Posts: 9,249
Central,PA
You need # 41 plates,Chicago Corvette,(708) 458-2500.They are now in Bend, OR.

Re: 340 6 bbl metering plates ?2 [Re: 62maxwgn] #2758445
04/01/20 03:25 PM
04/01/20 03:25 PM
Joined: Aug 2003
Posts: 34,973
Bend,OR USA
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Cab_Burge Offline
I Win
Cab_Burge  Offline
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Joined: Aug 2003
Posts: 34,973
Bend,OR USA
Originally Posted by 62maxwgn
You need # 41 plates,Chicago Corvette,(708) 458-2500.They are now in Bend, OR.


I learn something new today, Thanks up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: 340 6 bbl metering plates ?2 [Re: calrobb2000] #2758451
04/01/20 03:33 PM
04/01/20 03:33 PM
Joined: Aug 2003
Posts: 34,973
Bend,OR USA
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Cab_Burge Offline
I Win
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Joined: Aug 2003
Posts: 34,973
Bend,OR USA
I have worked on several OEM stock 340 six packs, they came lean from the factory and needed jetting to help them run as good as they can at WOT.
How does your car drive with those plates in the carbs?
I have seen a lot of those type Holley metering plates converted to removeable jetting by drilling and tapping the bottom fuel inlet holes to #6x32 thread size and then use #6x32 blank brass set screws and drill them to the size (with a good quality numbered drill set) you want up scope
Don't change the center carb jetting on the 340 carbs tsk
IHTHs

Last edited by Cab_Burge; 04/01/20 03:35 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: 340 6 bbl metering plates ?2 [Re: 62maxwgn] #2758461
04/01/20 03:56 PM
04/01/20 03:56 PM
Joined: May 2012
Posts: 1,215
South Bend
John Brown Offline
pro stock
John Brown  Offline
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Joined: May 2012
Posts: 1,215
South Bend
Originally Posted by 62maxwgn
You need # 41 plates,Chicago Corvette,(708) 458-2500.They are now in Bend, OR.



Al Firke sell Chicago Corvette to someone else? I know he buys and sells shows, didn't know he was no longer involved with CC.


July 19th should be "Drive Like Rockford Day". R.I.P. Jimmie.
Re: 340 6 bbl metering plates ?2 [Re: John Brown] #2758551
04/01/20 06:40 PM
04/01/20 06:40 PM
Joined: Jan 2003
Posts: 3,087
Phila Pa
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scatpacktom Offline
master
scatpacktom  Offline
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Posts: 3,087
Phila Pa
Why don't you just fill in the holes and redrill them. Probably save a pile

Re: 340 6 bbl metering plates ?2 [Re: John Brown] #2758606
04/01/20 08:34 PM
04/01/20 08:34 PM
Joined: Jan 2003
Posts: 9,249
Central,PA
62maxwgn Offline
master
62maxwgn  Offline
master

Joined: Jan 2003
Posts: 9,249
Central,PA
Originally Posted by John Brown
Originally Posted by 62maxwgn
You need # 41 plates,Chicago Corvette,(708) 458-2500.They are now in Eugene, OR.



Al Firke sell Chicago Corvette to someone else? I know he buys and sells shows, didn't know he was no longer involved with CC.


I talk to Al a couple times a month,have known him for years,Chicago Corvette is still Chicago Corvette,Al moved the whole operation to Eugene,OR ,that is where all his family is located.

Re: 340 6 bbl metering plates ?2 [Re: 62maxwgn] #2758644
04/01/20 10:26 PM
04/01/20 10:26 PM
Joined: May 2012
Posts: 1,215
South Bend
John Brown Offline
pro stock
John Brown  Offline
pro stock

Joined: May 2012
Posts: 1,215
South Bend
Just asking. I have known him for years too. Just haven't run into him lately. May be a while to, what with area swap meets being put on hold.


July 19th should be "Drive Like Rockford Day". R.I.P. Jimmie.
Re: 340 6 bbl metering plates ?2 [Re: John Brown] #2758822
04/02/20 11:43 AM
04/02/20 11:43 AM
Joined: Jan 2010
Posts: 435
Los Osos, Ca
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CKessel Offline
mopar
CKessel  Offline
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Joined: Jan 2010
Posts: 435
Los Osos, Ca
I can't remember who it is but one of the aftermarket carb companies makes a plate that is set up to take jets. Does not make the bowls stick out any farther. Much easier to deal with. Yeah, not STOCK but who is going to pull a bowl to make sure its oe.


Carl Kessel
Re: 340 6 bbl metering plates ?2 [Re: CKessel] #2758845
04/02/20 12:40 PM
04/02/20 12:40 PM
Joined: Jan 2003
Posts: 9,249
Central,PA
62maxwgn Offline
master
62maxwgn  Offline
master

Joined: Jan 2003
Posts: 9,249
Central,PA
Originally Posted by CKessel
I can't remember who it is but one of the aftermarket carb companies makes a plate that is set up to take jets. Does not make the bowls stick out any farther. Much easier to deal with. Yeah, not STOCK but who is going to pull a bowl to make sure its oe.


Promax makes a jetable plate but it will cost you $150 a pair,or you can plug the metering hole on the bottom of the plate,drill into the passage from the bottom front,tap and you can jet your own.

Re: 340 6 bbl metering plates ?2 [Re: 62maxwgn] #2758981
04/02/20 03:30 PM
04/02/20 03:30 PM
Joined: Feb 2006
Posts: 544
TN
1DGEMAN Offline
mopar
1DGEMAN  Offline
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Joined: Feb 2006
Posts: 544
TN
I bought Quick fuel plates and have full adjustability.


Real Men shift for themselves
Re: 340 6 bbl metering plates ?2 [Re: CKessel] #2759105
04/02/20 07:56 PM
04/02/20 07:56 PM
Joined: Jan 2003
Posts: 1,503
Nebraska
4
4406bbl Offline
pro stock
4406bbl  Offline
pro stock
4

Joined: Jan 2003
Posts: 1,503
Nebraska
What should a stock set of #41 plates measure for idle restrictions, and main jet? I have a holley book but as we know the new 440 #34-35 plates made today are not the same as what was installed in 1970.

Holley book shows #41
.033 idle
.070 main jet restiction
Kinda find that main size small for a 1-3/4 holley barrel, and dyno tests I have saved thru the years show .079-.083 to net a 13-1 afr, still lean. An 850 holley, same barrels, uses a #80 jet, amd a power valve. So are new # 41 plates correct or too small?

Re: 340 6 bbl metering plates ?2 [Re: 4406bbl] #2759176
04/02/20 11:13 PM
04/02/20 11:13 PM
Joined: Jan 2003
Posts: 9,249
Central,PA
62maxwgn Offline
master
62maxwgn  Offline
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Joined: Jan 2003
Posts: 9,249
Central,PA
Originally Posted by 4406bbl
What should a stock set of #41 plates measure for idle restrictions, and main jet? I have a holley book but as we know the new 440 #34-35 plates made today are not the same as what was installed in 1970.

Holley book shows #41
.033 idle
.070 main jet restiction
Kinda find that main size small for a 1-3/4 holley barrel, and dyno tests I have saved thru the years show .079-.083 to net a 13-1 afr, still lean. An 850 holley, same barrels, uses a #80 jet, amd a power valve. So are new # 41 plates correct or too small?


I'm pretty sure it is in the old Direct Connection manual,I'll look tomorrow if not I have at least 3 sets of 41 plates,easy to measure.

Re: 340 6 bbl metering plates ?2 [Re: CKessel] #2759244
04/03/20 06:46 AM
04/03/20 06:46 AM
Joined: Jan 2003
Posts: 5,338
Abilene, Texas
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fastmark Offline
master
fastmark  Offline
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Joined: Jan 2003
Posts: 5,338
Abilene, Texas
Originally Posted by CKessel
I can't remember who it is but one of the aftermarket carb companies makes a plate that is set up to take jets. Does not make the bowls stick out any farther. Much easier to deal with. Yeah, not STOCK but who is going to pull a bowl to make sure its oe.


It’s Promax carbs. I just bought some for my customers 440-6 Bee. They sell the base for the rear carb that has the angled metering screws for easy access.

Re: 340 6 bbl metering plates ?2 [Re: 4406bbl] #2759252
04/03/20 07:09 AM
04/03/20 07:09 AM
Joined: Feb 2006
Posts: 544
TN
1DGEMAN Offline
mopar
1DGEMAN  Offline
mopar

Joined: Feb 2006
Posts: 544
TN
Originally Posted by 4406bbl
What should a stock set of #41 plates measure for idle restrictions, and main jet? I have a holley book but as we know the new 440 #34-35 plates made today are not the same as what was installed in 1970.

Holley book shows #41
.033 idle
.070 main jet restiction
Kinda find that main size small for a 1-3/4 holley barrel, and dyno tests I have saved thru the years show .079-.083 to net a 13-1 afr, still lean. An 850 holley, same barrels, uses a #80 jet, amd a power valve. So are new # 41 plates correct or too small?

Here is a list of the plates in my 340 carbs . The last 2 carbs are the replacement carbs. These were all pined.

LIST # DATE APP PLATE IAB HSB T JET D KILL BLEED IFR
4789 490 340 F 41 0.052 0.039 .086 .072 0.046 0.037
4789 500 340 F 16 0.052 0.039 .067 .079 0.047 0.028
4789 890 340F 41 0.052 0.039 .085 .073 0.045 0.037
4790 500 340 R 41 0.052 0.039 .086 .072 0.046 0.037
4790 850 340R 41 0.052 0.039 .085 .072 0.045 0.037
4790 3518 340 F 41 0.068 0.027 .086 .072 0.047 0.037
4790 3518 340 R 41 0.068 0.027 .086 .072 0.046 0.037




Real Men shift for themselves
Re: 340 6 bbl metering plates ?2 [Re: 1DGEMAN] #2759436
04/03/20 12:15 PM
04/03/20 12:15 PM
Joined: Jan 2003
Posts: 1,503
Nebraska
4
4406bbl Offline
pro stock
4406bbl  Offline
pro stock
4

Joined: Jan 2003
Posts: 1,503
Nebraska
Thanks 1, that info is gold, it looks like the replacment generic #41 plates are incorrect just like the #34-35 generic 440 plates. It could be that just the book is wrong I guess. To the OP if you went by the holley book to determine if your plates are drilled, that printed info at least is wrong for a 6bbl.

Does anybody have this same info for the 1970-440-6?

Re: 340 6 bbl metering plates ?2 [Re: 4406bbl] #2759464
04/03/20 01:22 PM
04/03/20 01:22 PM
Joined: Feb 2006
Posts: 544
TN
1DGEMAN Offline
mopar
1DGEMAN  Offline
mopar

Joined: Feb 2006
Posts: 544
TN
The only 440 carbs I have and they have been modified, Some one had pluged the kill bleed and I had to drill them out and make them adjustable.
LIST DATE APP PLATE IAB HSB T JET D KILL BLEED IFR
4382 3149 70 440 F 34 0.052 0.039 .089 .089 ADJ 0.037
4383 2039 70 440 R 34 0.052 0.039 .081 .085 ADJ 0.037
4383 3149 70 440 R 35 0.052 0.039 .097 .086 ADJ 0.037


Real Men shift for themselves
Re: 340 6 bbl metering plates ?2 [Re: 1DGEMAN] #2759807
04/04/20 12:48 PM
04/04/20 12:48 PM
Joined: Jul 2007
Posts: 286
St. Louis
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Imrare Offline
enthusiast
Imrare  Offline
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Joined: Jul 2007
Posts: 286
St. Louis
I have a 1970 340-6 rebuilt to stock specifications. Originally the engine would not run properly, I was unable to idle it down below 1,000 rpm. Eventually I determined the carburetor metering plates on the end carburetors had been re-drilled as well as an incorrect metering block (generic) for the center carburetor. After several conversations with Holley and the Technical Department they assureded me the 2300 series carburetors they are manufacturing (4789, 4790, 4791, 4792) are manufactured to the same exact specs as was manufactured in 1970. The tech was able to pull a metering block assembly for my 4792 center carb off of the line (Holley P/N 34R6611-4AM, $73.17) along with 2 #41 machined metering plates (Holley P/N 34R6153-41, $30.98 ea.).

I'm not sure what your problem is with the carbs., but check your center carb base plate for any sloppiness whatsoever. The slightest amount of play in your center carb base plate throttle body will have a significant effect on the idle characteristics. Also, check that the correct jets are installed, (#61 auto, #63 manual) as both of these were a problem with my set up as well. Another thing to check are the air/fuel adjustment needles. When I purchased my metering block from from Holley it came with new air/fuel mixture screws installed but when I still couldn't get a consistent smooth idle, I checked the needles on my end carburetors. Looking under a magnifying glass it was obvious all four needles had been filed or slightly bent or in some other way not perfect. I ordered 4 new needles from Holley (P/N 15-3QFT, $4.98) and that was the last piece of the puzzle.

After making these changes and of course a complete rebuild kit installed, the engine ran perfectly, just like it did and was supposed to in 1970. Unfortunately, this was a 2-year process (2 winters) in diagnosing the problem, eliminating all other potential problems like a vacuum leak, distributor vacuum advance, fuel, etc. etc. I even had the carburetors professionally rebuilt (twice) and the problems detailed above were not caught. It seems they put a nice dichromate finish on the carbs,installed a new rebuild kit, but never really "dug into" quality of the parts that made up the carburetors...

I guess what I'm saying is that if you are doing a stock rebuild on a stock engine...I would get the parts described from the manufacturer of the carburetors designed for that engine.

Re: 340 6 bbl metering plates ?2 [Re: Imrare] #2759908
04/04/20 02:31 PM
04/04/20 02:31 PM
Joined: Jan 2003
Posts: 1,503
Nebraska
4
4406bbl Offline
pro stock
4406bbl  Offline
pro stock
4

Joined: Jan 2003
Posts: 1,503
Nebraska
Originally Posted by Imrare
I have a 1970 340-6 rebuilt to stock specifications. Originally the engine would not run properly, I was unable to idle it down below 1,000 rpm. Eventually I determined the carburetor metering plates on the end carburetors had been re-drilled as well as an incorrect metering block (generic) for the center carburetor. After several conversations with Holley and the Technical Department they assureded me the 2300 series carburetors they are manufacturing (4789, 4790, 4791, 4792) are manufactured to the same exact specs as was manufactured in 1970. The tech was able to pull a metering block assembly for my 4792 center carb off of the line (Holley P/N 34R6611-4AM, $73.17) along with 2 #41 machined metering plates (Holley P/N 34R6153-41, $30.98 ea.).

I'm not sure what your problem is with the carbs., but check your center carb base plate for any sloppiness whatsoever. The slightest amount of play in your center carb base plate throttle body will have a significant effect on the idle characteristics. Also, check that the correct jets are installed, (#61 auto, #63 manual) as both of these were a problem with my set up as well. Another thing to check are the air/fuel adjustment needles. When I purchased my metering block from from Holley it came with new air/fuel mixture screws installed but when I still couldn't get a consistent smooth idle, I checked the needles on my end carburetors. Looking under a magnifying glass it was obvious all four needles had been filed or slightly bent or in some other way not perfect. I ordered 4 new needles from Holley (P/N 15-3QFT, $4.98) and that was the last piece of the puzzle.

After making these changes and of course a complete rebuild kit installed, the engine ran perfectly, just like it did and was supposed to in 1970. Unfortunately, this was a 2-year process (2 winters) in diagnosing the problem, eliminating all other potential problems like a vacuum leak, distributor vacuum advance, fuel, etc. etc. I even had the carburetors professionally rebuilt (twice) and the problems detailed above were not caught. It seems they put a nice dichromate finish on the carbs,installed a new rebuild kit, but never really "dug into" quality of the parts that made up the carburetors...

I guess what I'm saying is that if you are doing a stock rebuild on a stock engine...I would get the parts described from the manufacturer of the carburetors designed for that engine.


Did you happen to measure the idle feed and jet sizes of the #41 new vs old plates? I also know the qft needles are not the same as stock baseplates used, stock needles are longer and thinner at the needle end. The qft match the metering blocks, not the baseplates. I just wish we had a baseline of all the stock designed restrictions so we could tell what has been drilled or not. The book specs for #41-34-35 plates do not match what most find in their 1970 carbs.

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